1 //===- MCExpr.cpp - Assembly Level Expression Implementation --------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #include "llvm/MC/MCExpr.h" 10 #include "llvm/ADT/Statistic.h" 11 #include "llvm/ADT/StringExtras.h" 12 #include "llvm/ADT/StringSwitch.h" 13 #include "llvm/Config/llvm-config.h" 14 #include "llvm/MC/MCAsmBackend.h" 15 #include "llvm/MC/MCAsmInfo.h" 16 #include "llvm/MC/MCAsmLayout.h" 17 #include "llvm/MC/MCAssembler.h" 18 #include "llvm/MC/MCContext.h" 19 #include "llvm/MC/MCObjectWriter.h" 20 #include "llvm/MC/MCSymbol.h" 21 #include "llvm/MC/MCValue.h" 22 #include "llvm/Support/Casting.h" 23 #include "llvm/Support/Compiler.h" 24 #include "llvm/Support/Debug.h" 25 #include "llvm/Support/ErrorHandling.h" 26 #include "llvm/Support/raw_ostream.h" 27 #include <cassert> 28 #include <cstdint> 29 30 using namespace llvm; 31 32 #define DEBUG_TYPE "mcexpr" 33 34 namespace { 35 namespace stats { 36 37 STATISTIC(MCExprEvaluate, "Number of MCExpr evaluations"); 38 39 } // end namespace stats 40 } // end anonymous namespace 41 42 void MCExpr::print(raw_ostream &OS, const MCAsmInfo *MAI, bool InParens) const { 43 switch (getKind()) { 44 case MCExpr::Target: 45 return cast<MCTargetExpr>(this)->printImpl(OS, MAI); 46 case MCExpr::Constant: { 47 auto Value = cast<MCConstantExpr>(*this).getValue(); 48 auto PrintInHex = cast<MCConstantExpr>(*this).useHexFormat(); 49 auto SizeInBytes = cast<MCConstantExpr>(*this).getSizeInBytes(); 50 if (PrintInHex) 51 switch (SizeInBytes) { 52 default: 53 OS << "0x" << Twine::utohexstr(Value); 54 break; 55 case 1: 56 OS << format("0x%02" PRIx64, Value); 57 break; 58 case 2: 59 OS << format("0x%04" PRIx64, Value); 60 break; 61 case 4: 62 OS << format("0x%08" PRIx64, Value); 63 break; 64 case 8: 65 OS << format("0x%016" PRIx64, Value); 66 break; 67 } 68 else 69 OS << Value; 70 return; 71 } 72 case MCExpr::SymbolRef: { 73 const MCSymbolRefExpr &SRE = cast<MCSymbolRefExpr>(*this); 74 const MCSymbol &Sym = SRE.getSymbol(); 75 // Parenthesize names that start with $ so that they don't look like 76 // absolute names. 77 bool UseParens = 78 !InParens && !Sym.getName().empty() && Sym.getName()[0] == '$'; 79 if (UseParens) { 80 OS << '('; 81 Sym.print(OS, MAI); 82 OS << ')'; 83 } else 84 Sym.print(OS, MAI); 85 86 if (SRE.getKind() != MCSymbolRefExpr::VK_None) 87 SRE.printVariantKind(OS); 88 89 return; 90 } 91 92 case MCExpr::Unary: { 93 const MCUnaryExpr &UE = cast<MCUnaryExpr>(*this); 94 switch (UE.getOpcode()) { 95 case MCUnaryExpr::LNot: OS << '!'; break; 96 case MCUnaryExpr::Minus: OS << '-'; break; 97 case MCUnaryExpr::Not: OS << '~'; break; 98 case MCUnaryExpr::Plus: OS << '+'; break; 99 } 100 bool Binary = UE.getSubExpr()->getKind() == MCExpr::Binary; 101 if (Binary) OS << "("; 102 UE.getSubExpr()->print(OS, MAI); 103 if (Binary) OS << ")"; 104 return; 105 } 106 107 case MCExpr::Binary: { 108 const MCBinaryExpr &BE = cast<MCBinaryExpr>(*this); 109 110 // Only print parens around the LHS if it is non-trivial. 111 if (isa<MCConstantExpr>(BE.getLHS()) || isa<MCSymbolRefExpr>(BE.getLHS())) { 112 BE.getLHS()->print(OS, MAI); 113 } else { 114 OS << '('; 115 BE.getLHS()->print(OS, MAI); 116 OS << ')'; 117 } 118 119 switch (BE.getOpcode()) { 120 case MCBinaryExpr::Add: 121 // Print "X-42" instead of "X+-42". 122 if (const MCConstantExpr *RHSC = dyn_cast<MCConstantExpr>(BE.getRHS())) { 123 if (RHSC->getValue() < 0) { 124 OS << RHSC->getValue(); 125 return; 126 } 127 } 128 129 OS << '+'; 130 break; 131 case MCBinaryExpr::AShr: OS << ">>"; break; 132 case MCBinaryExpr::And: OS << '&'; break; 133 case MCBinaryExpr::Div: OS << '/'; break; 134 case MCBinaryExpr::EQ: OS << "=="; break; 135 case MCBinaryExpr::GT: OS << '>'; break; 136 case MCBinaryExpr::GTE: OS << ">="; break; 137 case MCBinaryExpr::LAnd: OS << "&&"; break; 138 case MCBinaryExpr::LOr: OS << "||"; break; 139 case MCBinaryExpr::LShr: OS << ">>"; break; 140 case MCBinaryExpr::LT: OS << '<'; break; 141 case MCBinaryExpr::LTE: OS << "<="; break; 142 case MCBinaryExpr::Mod: OS << '%'; break; 143 case MCBinaryExpr::Mul: OS << '*'; break; 144 case MCBinaryExpr::NE: OS << "!="; break; 145 case MCBinaryExpr::Or: OS << '|'; break; 146 case MCBinaryExpr::Shl: OS << "<<"; break; 147 case MCBinaryExpr::Sub: OS << '-'; break; 148 case MCBinaryExpr::Xor: OS << '^'; break; 149 } 150 151 // Only print parens around the LHS if it is non-trivial. 152 if (isa<MCConstantExpr>(BE.getRHS()) || isa<MCSymbolRefExpr>(BE.getRHS())) { 153 BE.getRHS()->print(OS, MAI); 154 } else { 155 OS << '('; 156 BE.getRHS()->print(OS, MAI); 157 OS << ')'; 158 } 159 return; 160 } 161 } 162 163 llvm_unreachable("Invalid expression kind!"); 164 } 165 166 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) 167 LLVM_DUMP_METHOD void MCExpr::dump() const { 168 dbgs() << *this; 169 dbgs() << '\n'; 170 } 171 #endif 172 173 /* *** */ 174 175 const MCBinaryExpr *MCBinaryExpr::create(Opcode Opc, const MCExpr *LHS, 176 const MCExpr *RHS, MCContext &Ctx, 177 SMLoc Loc) { 178 return new (Ctx) MCBinaryExpr(Opc, LHS, RHS, Loc); 179 } 180 181 const MCUnaryExpr *MCUnaryExpr::create(Opcode Opc, const MCExpr *Expr, 182 MCContext &Ctx, SMLoc Loc) { 183 return new (Ctx) MCUnaryExpr(Opc, Expr, Loc); 184 } 185 186 const MCConstantExpr *MCConstantExpr::create(int64_t Value, MCContext &Ctx, 187 bool PrintInHex, 188 unsigned SizeInBytes) { 189 return new (Ctx) MCConstantExpr(Value, PrintInHex, SizeInBytes); 190 } 191 192 /* *** */ 193 194 MCSymbolRefExpr::MCSymbolRefExpr(const MCSymbol *Symbol, VariantKind Kind, 195 const MCAsmInfo *MAI, SMLoc Loc) 196 : MCExpr(MCExpr::SymbolRef, Loc), Kind(Kind), 197 UseParensForSymbolVariant(MAI->useParensForSymbolVariant()), 198 HasSubsectionsViaSymbols(MAI->hasSubsectionsViaSymbols()), 199 Symbol(Symbol) { 200 assert(Symbol); 201 } 202 203 const MCSymbolRefExpr *MCSymbolRefExpr::create(const MCSymbol *Sym, 204 VariantKind Kind, 205 MCContext &Ctx, SMLoc Loc) { 206 return new (Ctx) MCSymbolRefExpr(Sym, Kind, Ctx.getAsmInfo(), Loc); 207 } 208 209 const MCSymbolRefExpr *MCSymbolRefExpr::create(StringRef Name, VariantKind Kind, 210 MCContext &Ctx) { 211 return create(Ctx.getOrCreateSymbol(Name), Kind, Ctx); 212 } 213 214 StringRef MCSymbolRefExpr::getVariantKindName(VariantKind Kind) { 215 switch (Kind) { 216 case VK_Invalid: return "<<invalid>>"; 217 case VK_None: return "<<none>>"; 218 219 case VK_DTPOFF: return "DTPOFF"; 220 case VK_DTPREL: return "DTPREL"; 221 case VK_GOT: return "GOT"; 222 case VK_GOTOFF: return "GOTOFF"; 223 case VK_GOTREL: return "GOTREL"; 224 case VK_PCREL: return "PCREL"; 225 case VK_GOTPCREL: return "GOTPCREL"; 226 case VK_GOTTPOFF: return "GOTTPOFF"; 227 case VK_INDNTPOFF: return "INDNTPOFF"; 228 case VK_NTPOFF: return "NTPOFF"; 229 case VK_GOTNTPOFF: return "GOTNTPOFF"; 230 case VK_PLT: return "PLT"; 231 case VK_TLSGD: return "TLSGD"; 232 case VK_TLSLD: return "TLSLD"; 233 case VK_TLSLDM: return "TLSLDM"; 234 case VK_TPOFF: return "TPOFF"; 235 case VK_TPREL: return "TPREL"; 236 case VK_TLSCALL: return "tlscall"; 237 case VK_TLSDESC: return "tlsdesc"; 238 case VK_TLVP: return "TLVP"; 239 case VK_TLVPPAGE: return "TLVPPAGE"; 240 case VK_TLVPPAGEOFF: return "TLVPPAGEOFF"; 241 case VK_PAGE: return "PAGE"; 242 case VK_PAGEOFF: return "PAGEOFF"; 243 case VK_GOTPAGE: return "GOTPAGE"; 244 case VK_GOTPAGEOFF: return "GOTPAGEOFF"; 245 case VK_SECREL: return "SECREL32"; 246 case VK_SIZE: return "SIZE"; 247 case VK_WEAKREF: return "WEAKREF"; 248 case VK_X86_ABS8: return "ABS8"; 249 case VK_ARM_NONE: return "none"; 250 case VK_ARM_GOT_PREL: return "GOT_PREL"; 251 case VK_ARM_TARGET1: return "target1"; 252 case VK_ARM_TARGET2: return "target2"; 253 case VK_ARM_PREL31: return "prel31"; 254 case VK_ARM_SBREL: return "sbrel"; 255 case VK_ARM_TLSLDO: return "tlsldo"; 256 case VK_ARM_TLSDESCSEQ: return "tlsdescseq"; 257 case VK_AVR_NONE: return "none"; 258 case VK_AVR_LO8: return "lo8"; 259 case VK_AVR_HI8: return "hi8"; 260 case VK_AVR_HLO8: return "hlo8"; 261 case VK_AVR_DIFF8: return "diff8"; 262 case VK_AVR_DIFF16: return "diff16"; 263 case VK_AVR_DIFF32: return "diff32"; 264 case VK_PPC_LO: return "l"; 265 case VK_PPC_HI: return "h"; 266 case VK_PPC_HA: return "ha"; 267 case VK_PPC_HIGH: return "high"; 268 case VK_PPC_HIGHA: return "higha"; 269 case VK_PPC_HIGHER: return "higher"; 270 case VK_PPC_HIGHERA: return "highera"; 271 case VK_PPC_HIGHEST: return "highest"; 272 case VK_PPC_HIGHESTA: return "highesta"; 273 case VK_PPC_GOT_LO: return "got@l"; 274 case VK_PPC_GOT_HI: return "got@h"; 275 case VK_PPC_GOT_HA: return "got@ha"; 276 case VK_PPC_TOCBASE: return "tocbase"; 277 case VK_PPC_TOC: return "toc"; 278 case VK_PPC_TOC_LO: return "toc@l"; 279 case VK_PPC_TOC_HI: return "toc@h"; 280 case VK_PPC_TOC_HA: return "toc@ha"; 281 case VK_PPC_U: return "u"; 282 case VK_PPC_L: return "l"; 283 case VK_PPC_DTPMOD: return "dtpmod"; 284 case VK_PPC_TPREL_LO: return "tprel@l"; 285 case VK_PPC_TPREL_HI: return "tprel@h"; 286 case VK_PPC_TPREL_HA: return "tprel@ha"; 287 case VK_PPC_TPREL_HIGH: return "tprel@high"; 288 case VK_PPC_TPREL_HIGHA: return "tprel@higha"; 289 case VK_PPC_TPREL_HIGHER: return "tprel@higher"; 290 case VK_PPC_TPREL_HIGHERA: return "tprel@highera"; 291 case VK_PPC_TPREL_HIGHEST: return "tprel@highest"; 292 case VK_PPC_TPREL_HIGHESTA: return "tprel@highesta"; 293 case VK_PPC_DTPREL_LO: return "dtprel@l"; 294 case VK_PPC_DTPREL_HI: return "dtprel@h"; 295 case VK_PPC_DTPREL_HA: return "dtprel@ha"; 296 case VK_PPC_DTPREL_HIGH: return "dtprel@high"; 297 case VK_PPC_DTPREL_HIGHA: return "dtprel@higha"; 298 case VK_PPC_DTPREL_HIGHER: return "dtprel@higher"; 299 case VK_PPC_DTPREL_HIGHERA: return "dtprel@highera"; 300 case VK_PPC_DTPREL_HIGHEST: return "dtprel@highest"; 301 case VK_PPC_DTPREL_HIGHESTA: return "dtprel@highesta"; 302 case VK_PPC_GOT_TPREL: return "got@tprel"; 303 case VK_PPC_GOT_TPREL_LO: return "got@tprel@l"; 304 case VK_PPC_GOT_TPREL_HI: return "got@tprel@h"; 305 case VK_PPC_GOT_TPREL_HA: return "got@tprel@ha"; 306 case VK_PPC_GOT_DTPREL: return "got@dtprel"; 307 case VK_PPC_GOT_DTPREL_LO: return "got@dtprel@l"; 308 case VK_PPC_GOT_DTPREL_HI: return "got@dtprel@h"; 309 case VK_PPC_GOT_DTPREL_HA: return "got@dtprel@ha"; 310 case VK_PPC_TLS: return "tls"; 311 case VK_PPC_GOT_TLSGD: return "got@tlsgd"; 312 case VK_PPC_GOT_TLSGD_LO: return "got@tlsgd@l"; 313 case VK_PPC_GOT_TLSGD_HI: return "got@tlsgd@h"; 314 case VK_PPC_GOT_TLSGD_HA: return "got@tlsgd@ha"; 315 case VK_PPC_TLSGD: return "tlsgd"; 316 case VK_PPC_GOT_TLSLD: return "got@tlsld"; 317 case VK_PPC_GOT_TLSLD_LO: return "got@tlsld@l"; 318 case VK_PPC_GOT_TLSLD_HI: return "got@tlsld@h"; 319 case VK_PPC_GOT_TLSLD_HA: return "got@tlsld@ha"; 320 case VK_PPC_TLSLD: return "tlsld"; 321 case VK_PPC_LOCAL: return "local"; 322 case VK_COFF_IMGREL32: return "IMGREL"; 323 case VK_Hexagon_LO16: return "LO16"; 324 case VK_Hexagon_HI16: return "HI16"; 325 case VK_Hexagon_GPREL: return "GPREL"; 326 case VK_Hexagon_GD_GOT: return "GDGOT"; 327 case VK_Hexagon_LD_GOT: return "LDGOT"; 328 case VK_Hexagon_GD_PLT: return "GDPLT"; 329 case VK_Hexagon_LD_PLT: return "LDPLT"; 330 case VK_Hexagon_IE: return "IE"; 331 case VK_Hexagon_IE_GOT: return "IEGOT"; 332 case VK_WASM_TYPEINDEX: return "TYPEINDEX"; 333 case VK_WASM_MBREL: return "MBREL"; 334 case VK_WASM_TBREL: return "TBREL"; 335 case VK_AMDGPU_GOTPCREL32_LO: return "gotpcrel32@lo"; 336 case VK_AMDGPU_GOTPCREL32_HI: return "gotpcrel32@hi"; 337 case VK_AMDGPU_REL32_LO: return "rel32@lo"; 338 case VK_AMDGPU_REL32_HI: return "rel32@hi"; 339 case VK_AMDGPU_REL64: return "rel64"; 340 case VK_AMDGPU_ABS32_LO: return "abs32@lo"; 341 case VK_AMDGPU_ABS32_HI: return "abs32@hi"; 342 } 343 llvm_unreachable("Invalid variant kind"); 344 } 345 346 MCSymbolRefExpr::VariantKind 347 MCSymbolRefExpr::getVariantKindForName(StringRef Name) { 348 return StringSwitch<VariantKind>(Name.lower()) 349 .Case("dtprel", VK_DTPREL) 350 .Case("dtpoff", VK_DTPOFF) 351 .Case("got", VK_GOT) 352 .Case("gotoff", VK_GOTOFF) 353 .Case("gotrel", VK_GOTREL) 354 .Case("pcrel", VK_PCREL) 355 .Case("gotpcrel", VK_GOTPCREL) 356 .Case("gottpoff", VK_GOTTPOFF) 357 .Case("indntpoff", VK_INDNTPOFF) 358 .Case("ntpoff", VK_NTPOFF) 359 .Case("gotntpoff", VK_GOTNTPOFF) 360 .Case("plt", VK_PLT) 361 .Case("tlscall", VK_TLSCALL) 362 .Case("tlsdesc", VK_TLSDESC) 363 .Case("tlsgd", VK_TLSGD) 364 .Case("tlsld", VK_TLSLD) 365 .Case("tlsldm", VK_TLSLDM) 366 .Case("tpoff", VK_TPOFF) 367 .Case("tprel", VK_TPREL) 368 .Case("tlvp", VK_TLVP) 369 .Case("tlvppage", VK_TLVPPAGE) 370 .Case("tlvppageoff", VK_TLVPPAGEOFF) 371 .Case("page", VK_PAGE) 372 .Case("pageoff", VK_PAGEOFF) 373 .Case("gotpage", VK_GOTPAGE) 374 .Case("gotpageoff", VK_GOTPAGEOFF) 375 .Case("imgrel", VK_COFF_IMGREL32) 376 .Case("secrel32", VK_SECREL) 377 .Case("size", VK_SIZE) 378 .Case("abs8", VK_X86_ABS8) 379 .Case("l", VK_PPC_LO) 380 .Case("h", VK_PPC_HI) 381 .Case("ha", VK_PPC_HA) 382 .Case("high", VK_PPC_HIGH) 383 .Case("higha", VK_PPC_HIGHA) 384 .Case("higher", VK_PPC_HIGHER) 385 .Case("highera", VK_PPC_HIGHERA) 386 .Case("highest", VK_PPC_HIGHEST) 387 .Case("highesta", VK_PPC_HIGHESTA) 388 .Case("got@l", VK_PPC_GOT_LO) 389 .Case("got@h", VK_PPC_GOT_HI) 390 .Case("got@ha", VK_PPC_GOT_HA) 391 .Case("local", VK_PPC_LOCAL) 392 .Case("tocbase", VK_PPC_TOCBASE) 393 .Case("toc", VK_PPC_TOC) 394 .Case("toc@l", VK_PPC_TOC_LO) 395 .Case("toc@h", VK_PPC_TOC_HI) 396 .Case("toc@ha", VK_PPC_TOC_HA) 397 .Case("u", VK_PPC_U) 398 .Case("l", VK_PPC_L) 399 .Case("tls", VK_PPC_TLS) 400 .Case("dtpmod", VK_PPC_DTPMOD) 401 .Case("tprel@l", VK_PPC_TPREL_LO) 402 .Case("tprel@h", VK_PPC_TPREL_HI) 403 .Case("tprel@ha", VK_PPC_TPREL_HA) 404 .Case("tprel@high", VK_PPC_TPREL_HIGH) 405 .Case("tprel@higha", VK_PPC_TPREL_HIGHA) 406 .Case("tprel@higher", VK_PPC_TPREL_HIGHER) 407 .Case("tprel@highera", VK_PPC_TPREL_HIGHERA) 408 .Case("tprel@highest", VK_PPC_TPREL_HIGHEST) 409 .Case("tprel@highesta", VK_PPC_TPREL_HIGHESTA) 410 .Case("dtprel@l", VK_PPC_DTPREL_LO) 411 .Case("dtprel@h", VK_PPC_DTPREL_HI) 412 .Case("dtprel@ha", VK_PPC_DTPREL_HA) 413 .Case("dtprel@high", VK_PPC_DTPREL_HIGH) 414 .Case("dtprel@higha", VK_PPC_DTPREL_HIGHA) 415 .Case("dtprel@higher", VK_PPC_DTPREL_HIGHER) 416 .Case("dtprel@highera", VK_PPC_DTPREL_HIGHERA) 417 .Case("dtprel@highest", VK_PPC_DTPREL_HIGHEST) 418 .Case("dtprel@highesta", VK_PPC_DTPREL_HIGHESTA) 419 .Case("got@tprel", VK_PPC_GOT_TPREL) 420 .Case("got@tprel@l", VK_PPC_GOT_TPREL_LO) 421 .Case("got@tprel@h", VK_PPC_GOT_TPREL_HI) 422 .Case("got@tprel@ha", VK_PPC_GOT_TPREL_HA) 423 .Case("got@dtprel", VK_PPC_GOT_DTPREL) 424 .Case("got@dtprel@l", VK_PPC_GOT_DTPREL_LO) 425 .Case("got@dtprel@h", VK_PPC_GOT_DTPREL_HI) 426 .Case("got@dtprel@ha", VK_PPC_GOT_DTPREL_HA) 427 .Case("got@tlsgd", VK_PPC_GOT_TLSGD) 428 .Case("got@tlsgd@l", VK_PPC_GOT_TLSGD_LO) 429 .Case("got@tlsgd@h", VK_PPC_GOT_TLSGD_HI) 430 .Case("got@tlsgd@ha", VK_PPC_GOT_TLSGD_HA) 431 .Case("got@tlsld", VK_PPC_GOT_TLSLD) 432 .Case("got@tlsld@l", VK_PPC_GOT_TLSLD_LO) 433 .Case("got@tlsld@h", VK_PPC_GOT_TLSLD_HI) 434 .Case("got@tlsld@ha", VK_PPC_GOT_TLSLD_HA) 435 .Case("gdgot", VK_Hexagon_GD_GOT) 436 .Case("gdplt", VK_Hexagon_GD_PLT) 437 .Case("iegot", VK_Hexagon_IE_GOT) 438 .Case("ie", VK_Hexagon_IE) 439 .Case("ldgot", VK_Hexagon_LD_GOT) 440 .Case("ldplt", VK_Hexagon_LD_PLT) 441 .Case("none", VK_ARM_NONE) 442 .Case("got_prel", VK_ARM_GOT_PREL) 443 .Case("target1", VK_ARM_TARGET1) 444 .Case("target2", VK_ARM_TARGET2) 445 .Case("prel31", VK_ARM_PREL31) 446 .Case("sbrel", VK_ARM_SBREL) 447 .Case("tlsldo", VK_ARM_TLSLDO) 448 .Case("lo8", VK_AVR_LO8) 449 .Case("hi8", VK_AVR_HI8) 450 .Case("hlo8", VK_AVR_HLO8) 451 .Case("typeindex", VK_WASM_TYPEINDEX) 452 .Case("tbrel", VK_WASM_TBREL) 453 .Case("mbrel", VK_WASM_MBREL) 454 .Case("gotpcrel32@lo", VK_AMDGPU_GOTPCREL32_LO) 455 .Case("gotpcrel32@hi", VK_AMDGPU_GOTPCREL32_HI) 456 .Case("rel32@lo", VK_AMDGPU_REL32_LO) 457 .Case("rel32@hi", VK_AMDGPU_REL32_HI) 458 .Case("rel64", VK_AMDGPU_REL64) 459 .Case("abs32@lo", VK_AMDGPU_ABS32_LO) 460 .Case("abs32@hi", VK_AMDGPU_ABS32_HI) 461 .Default(VK_Invalid); 462 } 463 464 void MCSymbolRefExpr::printVariantKind(raw_ostream &OS) const { 465 if (UseParensForSymbolVariant) 466 OS << '(' << MCSymbolRefExpr::getVariantKindName(getKind()) << ')'; 467 else 468 OS << '@' << MCSymbolRefExpr::getVariantKindName(getKind()); 469 } 470 471 /* *** */ 472 473 void MCTargetExpr::anchor() {} 474 475 /* *** */ 476 477 bool MCExpr::evaluateAsAbsolute(int64_t &Res) const { 478 return evaluateAsAbsolute(Res, nullptr, nullptr, nullptr, false); 479 } 480 481 bool MCExpr::evaluateAsAbsolute(int64_t &Res, 482 const MCAsmLayout &Layout) const { 483 return evaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, nullptr, false); 484 } 485 486 bool MCExpr::evaluateAsAbsolute(int64_t &Res, 487 const MCAsmLayout &Layout, 488 const SectionAddrMap &Addrs) const { 489 // Setting InSet causes us to absolutize differences across sections and that 490 // is what the MachO writer uses Addrs for. 491 return evaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, &Addrs, true); 492 } 493 494 bool MCExpr::evaluateAsAbsolute(int64_t &Res, const MCAssembler &Asm) const { 495 return evaluateAsAbsolute(Res, &Asm, nullptr, nullptr, false); 496 } 497 498 bool MCExpr::evaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm) const { 499 return evaluateAsAbsolute(Res, Asm, nullptr, nullptr, false); 500 } 501 502 bool MCExpr::evaluateKnownAbsolute(int64_t &Res, 503 const MCAsmLayout &Layout) const { 504 return evaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, nullptr, 505 true); 506 } 507 508 bool MCExpr::evaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm, 509 const MCAsmLayout *Layout, 510 const SectionAddrMap *Addrs, bool InSet) const { 511 MCValue Value; 512 513 // Fast path constants. 514 if (const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(this)) { 515 Res = CE->getValue(); 516 return true; 517 } 518 519 bool IsRelocatable = 520 evaluateAsRelocatableImpl(Value, Asm, Layout, nullptr, Addrs, InSet); 521 522 // Record the current value. 523 Res = Value.getConstant(); 524 525 return IsRelocatable && Value.isAbsolute(); 526 } 527 528 /// Helper method for \see EvaluateSymbolAdd(). 529 static void AttemptToFoldSymbolOffsetDifference( 530 const MCAssembler *Asm, const MCAsmLayout *Layout, 531 const SectionAddrMap *Addrs, bool InSet, const MCSymbolRefExpr *&A, 532 const MCSymbolRefExpr *&B, int64_t &Addend) { 533 if (!A || !B) 534 return; 535 536 const MCSymbol &SA = A->getSymbol(); 537 const MCSymbol &SB = B->getSymbol(); 538 539 if (SA.isUndefined() || SB.isUndefined()) 540 return; 541 542 if (!Asm->getWriter().isSymbolRefDifferenceFullyResolved(*Asm, A, B, InSet)) 543 return; 544 545 if (SA.getFragment() == SB.getFragment() && !SA.isVariable() && 546 !SA.isUnset() && !SB.isVariable() && !SB.isUnset()) { 547 Addend += (SA.getOffset() - SB.getOffset()); 548 549 // Pointers to Thumb symbols need to have their low-bit set to allow 550 // for interworking. 551 if (Asm->isThumbFunc(&SA)) 552 Addend |= 1; 553 554 // If symbol is labeled as micromips, we set low-bit to ensure 555 // correct offset in .gcc_except_table 556 if (Asm->getBackend().isMicroMips(&SA)) 557 Addend |= 1; 558 559 // Clear the symbol expr pointers to indicate we have folded these 560 // operands. 561 A = B = nullptr; 562 return; 563 } 564 565 if (!Layout) 566 return; 567 568 const MCSection &SecA = *SA.getFragment()->getParent(); 569 const MCSection &SecB = *SB.getFragment()->getParent(); 570 571 if ((&SecA != &SecB) && !Addrs) 572 return; 573 574 // Eagerly evaluate. 575 Addend += Layout->getSymbolOffset(A->getSymbol()) - 576 Layout->getSymbolOffset(B->getSymbol()); 577 if (Addrs && (&SecA != &SecB)) 578 Addend += (Addrs->lookup(&SecA) - Addrs->lookup(&SecB)); 579 580 // Pointers to Thumb symbols need to have their low-bit set to allow 581 // for interworking. 582 if (Asm->isThumbFunc(&SA)) 583 Addend |= 1; 584 585 // If symbol is labeled as micromips, we set low-bit to ensure 586 // correct offset in .gcc_except_table 587 if (Asm->getBackend().isMicroMips(&SA)) 588 Addend |= 1; 589 590 // Clear the symbol expr pointers to indicate we have folded these 591 // operands. 592 A = B = nullptr; 593 } 594 595 static bool canFold(const MCAssembler *Asm, const MCSymbolRefExpr *A, 596 const MCSymbolRefExpr *B, bool InSet) { 597 if (InSet) 598 return true; 599 600 if (!Asm->getBackend().requiresDiffExpressionRelocations()) 601 return true; 602 603 const MCSymbol &CheckSym = A ? A->getSymbol() : B->getSymbol(); 604 if (!CheckSym.isInSection()) 605 return true; 606 607 if (!CheckSym.getSection().hasInstructions()) 608 return true; 609 610 return false; 611 } 612 613 /// Evaluate the result of an add between (conceptually) two MCValues. 614 /// 615 /// This routine conceptually attempts to construct an MCValue: 616 /// Result = (Result_A - Result_B + Result_Cst) 617 /// from two MCValue's LHS and RHS where 618 /// Result = LHS + RHS 619 /// and 620 /// Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst). 621 /// 622 /// This routine attempts to aggressively fold the operands such that the result 623 /// is representable in an MCValue, but may not always succeed. 624 /// 625 /// \returns True on success, false if the result is not representable in an 626 /// MCValue. 627 628 /// NOTE: It is really important to have both the Asm and Layout arguments. 629 /// They might look redundant, but this function can be used before layout 630 /// is done (see the object streamer for example) and having the Asm argument 631 /// lets us avoid relaxations early. 632 static bool 633 EvaluateSymbolicAdd(const MCAssembler *Asm, const MCAsmLayout *Layout, 634 const SectionAddrMap *Addrs, bool InSet, const MCValue &LHS, 635 const MCSymbolRefExpr *RHS_A, const MCSymbolRefExpr *RHS_B, 636 int64_t RHS_Cst, MCValue &Res) { 637 // FIXME: This routine (and other evaluation parts) are *incredibly* sloppy 638 // about dealing with modifiers. This will ultimately bite us, one day. 639 const MCSymbolRefExpr *LHS_A = LHS.getSymA(); 640 const MCSymbolRefExpr *LHS_B = LHS.getSymB(); 641 int64_t LHS_Cst = LHS.getConstant(); 642 643 // Fold the result constant immediately. 644 int64_t Result_Cst = LHS_Cst + RHS_Cst; 645 646 assert((!Layout || Asm) && 647 "Must have an assembler object if layout is given!"); 648 649 // If we have a layout, we can fold resolved differences. Do not do this if 650 // the backend requires this to be emitted as individual relocations, unless 651 // the InSet flag is set to get the current difference anyway (used for 652 // example to calculate symbol sizes). 653 if (Asm && canFold(Asm, LHS_A, LHS_B, InSet)) { 654 // First, fold out any differences which are fully resolved. By 655 // reassociating terms in 656 // Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst). 657 // we have the four possible differences: 658 // (LHS_A - LHS_B), 659 // (LHS_A - RHS_B), 660 // (RHS_A - LHS_B), 661 // (RHS_A - RHS_B). 662 // Since we are attempting to be as aggressive as possible about folding, we 663 // attempt to evaluate each possible alternative. 664 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, LHS_B, 665 Result_Cst); 666 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, RHS_B, 667 Result_Cst); 668 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, LHS_B, 669 Result_Cst); 670 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, RHS_B, 671 Result_Cst); 672 } 673 674 // We can't represent the addition or subtraction of two symbols. 675 if ((LHS_A && RHS_A) || (LHS_B && RHS_B)) 676 return false; 677 678 // At this point, we have at most one additive symbol and one subtractive 679 // symbol -- find them. 680 const MCSymbolRefExpr *A = LHS_A ? LHS_A : RHS_A; 681 const MCSymbolRefExpr *B = LHS_B ? LHS_B : RHS_B; 682 683 Res = MCValue::get(A, B, Result_Cst); 684 return true; 685 } 686 687 bool MCExpr::evaluateAsRelocatable(MCValue &Res, 688 const MCAsmLayout *Layout, 689 const MCFixup *Fixup) const { 690 MCAssembler *Assembler = Layout ? &Layout->getAssembler() : nullptr; 691 return evaluateAsRelocatableImpl(Res, Assembler, Layout, Fixup, nullptr, 692 false); 693 } 694 695 bool MCExpr::evaluateAsValue(MCValue &Res, const MCAsmLayout &Layout) const { 696 MCAssembler *Assembler = &Layout.getAssembler(); 697 return evaluateAsRelocatableImpl(Res, Assembler, &Layout, nullptr, nullptr, 698 true); 699 } 700 701 static bool canExpand(const MCSymbol &Sym, bool InSet) { 702 const MCExpr *Expr = Sym.getVariableValue(); 703 const auto *Inner = dyn_cast<MCSymbolRefExpr>(Expr); 704 if (Inner) { 705 if (Inner->getKind() == MCSymbolRefExpr::VK_WEAKREF) 706 return false; 707 } 708 709 if (InSet) 710 return true; 711 return !Sym.isInSection(); 712 } 713 714 bool MCExpr::evaluateAsRelocatableImpl(MCValue &Res, const MCAssembler *Asm, 715 const MCAsmLayout *Layout, 716 const MCFixup *Fixup, 717 const SectionAddrMap *Addrs, 718 bool InSet) const { 719 ++stats::MCExprEvaluate; 720 721 switch (getKind()) { 722 case Target: 723 return cast<MCTargetExpr>(this)->evaluateAsRelocatableImpl(Res, Layout, 724 Fixup); 725 726 case Constant: 727 Res = MCValue::get(cast<MCConstantExpr>(this)->getValue()); 728 return true; 729 730 case SymbolRef: { 731 const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this); 732 const MCSymbol &Sym = SRE->getSymbol(); 733 734 // Evaluate recursively if this is a variable. 735 if (Sym.isVariable() && SRE->getKind() == MCSymbolRefExpr::VK_None && 736 canExpand(Sym, InSet)) { 737 bool IsMachO = SRE->hasSubsectionsViaSymbols(); 738 if (Sym.getVariableValue()->evaluateAsRelocatableImpl( 739 Res, Asm, Layout, Fixup, Addrs, InSet || IsMachO)) { 740 if (!IsMachO) 741 return true; 742 743 const MCSymbolRefExpr *A = Res.getSymA(); 744 const MCSymbolRefExpr *B = Res.getSymB(); 745 // FIXME: This is small hack. Given 746 // a = b + 4 747 // .long a 748 // the OS X assembler will completely drop the 4. We should probably 749 // include it in the relocation or produce an error if that is not 750 // possible. 751 // Allow constant expressions. 752 if (!A && !B) 753 return true; 754 // Allows aliases with zero offset. 755 if (Res.getConstant() == 0 && (!A || !B)) 756 return true; 757 } 758 } 759 760 Res = MCValue::get(SRE, nullptr, 0); 761 return true; 762 } 763 764 case Unary: { 765 const MCUnaryExpr *AUE = cast<MCUnaryExpr>(this); 766 MCValue Value; 767 768 if (!AUE->getSubExpr()->evaluateAsRelocatableImpl(Value, Asm, Layout, Fixup, 769 Addrs, InSet)) 770 return false; 771 772 switch (AUE->getOpcode()) { 773 case MCUnaryExpr::LNot: 774 if (!Value.isAbsolute()) 775 return false; 776 Res = MCValue::get(!Value.getConstant()); 777 break; 778 case MCUnaryExpr::Minus: 779 /// -(a - b + const) ==> (b - a - const) 780 if (Value.getSymA() && !Value.getSymB()) 781 return false; 782 783 // The cast avoids undefined behavior if the constant is INT64_MIN. 784 Res = MCValue::get(Value.getSymB(), Value.getSymA(), 785 -(uint64_t)Value.getConstant()); 786 break; 787 case MCUnaryExpr::Not: 788 if (!Value.isAbsolute()) 789 return false; 790 Res = MCValue::get(~Value.getConstant()); 791 break; 792 case MCUnaryExpr::Plus: 793 Res = Value; 794 break; 795 } 796 797 return true; 798 } 799 800 case Binary: { 801 const MCBinaryExpr *ABE = cast<MCBinaryExpr>(this); 802 MCValue LHSValue, RHSValue; 803 804 if (!ABE->getLHS()->evaluateAsRelocatableImpl(LHSValue, Asm, Layout, Fixup, 805 Addrs, InSet) || 806 !ABE->getRHS()->evaluateAsRelocatableImpl(RHSValue, Asm, Layout, Fixup, 807 Addrs, InSet)) { 808 // Check if both are Target Expressions, see if we can compare them. 809 if (const MCTargetExpr *L = dyn_cast<MCTargetExpr>(ABE->getLHS())) 810 if (const MCTargetExpr *R = cast<MCTargetExpr>(ABE->getRHS())) { 811 switch (ABE->getOpcode()) { 812 case MCBinaryExpr::EQ: 813 Res = MCValue::get((L->isEqualTo(R)) ? -1 : 0); 814 return true; 815 case MCBinaryExpr::NE: 816 Res = MCValue::get((R->isEqualTo(R)) ? 0 : -1); 817 return true; 818 default: break; 819 } 820 } 821 return false; 822 } 823 824 // We only support a few operations on non-constant expressions, handle 825 // those first. 826 if (!LHSValue.isAbsolute() || !RHSValue.isAbsolute()) { 827 switch (ABE->getOpcode()) { 828 default: 829 return false; 830 case MCBinaryExpr::Sub: 831 // Negate RHS and add. 832 // The cast avoids undefined behavior if the constant is INT64_MIN. 833 return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue, 834 RHSValue.getSymB(), RHSValue.getSymA(), 835 -(uint64_t)RHSValue.getConstant(), Res); 836 837 case MCBinaryExpr::Add: 838 return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue, 839 RHSValue.getSymA(), RHSValue.getSymB(), 840 RHSValue.getConstant(), Res); 841 } 842 } 843 844 // FIXME: We need target hooks for the evaluation. It may be limited in 845 // width, and gas defines the result of comparisons differently from 846 // Apple as. 847 int64_t LHS = LHSValue.getConstant(), RHS = RHSValue.getConstant(); 848 int64_t Result = 0; 849 auto Op = ABE->getOpcode(); 850 switch (Op) { 851 case MCBinaryExpr::AShr: Result = LHS >> RHS; break; 852 case MCBinaryExpr::Add: Result = LHS + RHS; break; 853 case MCBinaryExpr::And: Result = LHS & RHS; break; 854 case MCBinaryExpr::Div: 855 case MCBinaryExpr::Mod: 856 // Handle division by zero. gas just emits a warning and keeps going, 857 // we try to be stricter. 858 // FIXME: Currently the caller of this function has no way to understand 859 // we're bailing out because of 'division by zero'. Therefore, it will 860 // emit a 'expected relocatable expression' error. It would be nice to 861 // change this code to emit a better diagnostic. 862 if (RHS == 0) 863 return false; 864 if (ABE->getOpcode() == MCBinaryExpr::Div) 865 Result = LHS / RHS; 866 else 867 Result = LHS % RHS; 868 break; 869 case MCBinaryExpr::EQ: Result = LHS == RHS; break; 870 case MCBinaryExpr::GT: Result = LHS > RHS; break; 871 case MCBinaryExpr::GTE: Result = LHS >= RHS; break; 872 case MCBinaryExpr::LAnd: Result = LHS && RHS; break; 873 case MCBinaryExpr::LOr: Result = LHS || RHS; break; 874 case MCBinaryExpr::LShr: Result = uint64_t(LHS) >> uint64_t(RHS); break; 875 case MCBinaryExpr::LT: Result = LHS < RHS; break; 876 case MCBinaryExpr::LTE: Result = LHS <= RHS; break; 877 case MCBinaryExpr::Mul: Result = LHS * RHS; break; 878 case MCBinaryExpr::NE: Result = LHS != RHS; break; 879 case MCBinaryExpr::Or: Result = LHS | RHS; break; 880 case MCBinaryExpr::Shl: Result = uint64_t(LHS) << uint64_t(RHS); break; 881 case MCBinaryExpr::Sub: Result = LHS - RHS; break; 882 case MCBinaryExpr::Xor: Result = LHS ^ RHS; break; 883 } 884 885 switch (Op) { 886 default: 887 Res = MCValue::get(Result); 888 break; 889 case MCBinaryExpr::EQ: 890 case MCBinaryExpr::GT: 891 case MCBinaryExpr::GTE: 892 case MCBinaryExpr::LT: 893 case MCBinaryExpr::LTE: 894 case MCBinaryExpr::NE: 895 // A comparison operator returns a -1 if true and 0 if false. 896 Res = MCValue::get(Result ? -1 : 0); 897 break; 898 } 899 900 return true; 901 } 902 } 903 904 llvm_unreachable("Invalid assembly expression kind!"); 905 } 906 907 MCFragment *MCExpr::findAssociatedFragment() const { 908 switch (getKind()) { 909 case Target: 910 // We never look through target specific expressions. 911 return cast<MCTargetExpr>(this)->findAssociatedFragment(); 912 913 case Constant: 914 return MCSymbol::AbsolutePseudoFragment; 915 916 case SymbolRef: { 917 const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this); 918 const MCSymbol &Sym = SRE->getSymbol(); 919 return Sym.getFragment(); 920 } 921 922 case Unary: 923 return cast<MCUnaryExpr>(this)->getSubExpr()->findAssociatedFragment(); 924 925 case Binary: { 926 const MCBinaryExpr *BE = cast<MCBinaryExpr>(this); 927 MCFragment *LHS_F = BE->getLHS()->findAssociatedFragment(); 928 MCFragment *RHS_F = BE->getRHS()->findAssociatedFragment(); 929 930 // If either is absolute, return the other. 931 if (LHS_F == MCSymbol::AbsolutePseudoFragment) 932 return RHS_F; 933 if (RHS_F == MCSymbol::AbsolutePseudoFragment) 934 return LHS_F; 935 936 // Not always correct, but probably the best we can do without more context. 937 if (BE->getOpcode() == MCBinaryExpr::Sub) 938 return MCSymbol::AbsolutePseudoFragment; 939 940 // Otherwise, return the first non-null fragment. 941 return LHS_F ? LHS_F : RHS_F; 942 } 943 } 944 945 llvm_unreachable("Invalid assembly expression kind!"); 946 } 947